1. Field of the Invention
This invention relates to a male terminal for electrical connection, and more particularly this invention relates to an male terminal for electrical connection which can be fitted to female terminals of various sizes.
2. Description of the Prior Art
Examples of conventional male terminals for electrical connection are illustrated in FIGS. 1 and 2.
The conventional male terminal 1 as shown in FIG. 1 is a flat terminal which comprises a front portion constituting an electrical connecting section made of a tab strip 1a (hereinafter referred to as "tab") and a rear portion constituting a wire connecting section 1b to which an electrical wire (not shown) is connected. Further, the other conventional male terminal 2 as shown in FIG. 2 is a male terminal of bus bar type having three tabs 2a, 2b and 2c as an electrical contact. The male terminal 2 is formed by bending end portions of a metal sheet punched to a predetermined shape.
Recently, junction blocks are usually used for electrical connection in automobiles and household electric appliances and so forth. In the junction blocks, ready-made parts are used as relays and connectors to which male terminals are connected. Therefore, female terminals attached to the relays and connectors to which the male terminals are fitted are in great variety of sizes and shapes.
FIGS. 3 and 4 show examples of female terminals to which the male terminals are fitted. Specifically, the female terminal 3 as shown in FIG. 3 comprises a tab receptacle 3e and wire connecting section 3h. The tab receptacle 3e has protruding contact surfaces 3g which are formed by bending elongated portions of the opposite sides of a base plate 3f semicircularly, respectively, so as to leave a space having a width of "l" between the each protruding contact surface 3g and the base plate 3f. The width of "l" is substantially equivalent to the thickness of the tab of the male terminal thereby the tab can be positively fitted to the female terminal.
Specifically, shapes and sizes of the tabs of the male terminals, of course, have to correspond to the shapes and sizes of the tab receptacles of the female terminals.
The female terminal 4 as shown in FIG. 4 has the same construction as that of FIG. 3 except for the shape of the tab receptacle 4e, that is, the elongated portions of the opposite sides of a base plate 4f are bent like a substantially box shape.
Recently, however, since female terminals attached to electrical parts in a junction block are, as stated above, various in size and shape, it is required to adjust size and thickness of a tab of a male terminal which is connected to the female terminal so as to fit to the size and shape of the female terminal.
In this connection, as methods for adjusting the thickness of a tab of a male terminal, which is formed from a metal sheet having a thickness different from a width of a space of a tab receptacle of a female terminal, so as to fit various widths of tab receptacles, the following two prior art receptacles have been known. One is the method disclosed in the Publication of examined Japanese Utility Model Application No. 60-37819, which is shown in FIG. 5, and the other is the method of obtaining a tab of a male terminal having a desired thickness by press working of metal sheet having a thickness which is greater than the desired thickness.
In the former method, a thickness of a metal sheet forming a bus bar is set to the thickness of a tab that has the smallest thickness among tabs of the bus bar. When a tab 5 with a desired thickness which is larger than the thickness of the metal sheet is required, a protruding portion 5j is formed on the tab 5 by pressing the metal sheet 5i outwardly, as shown in FIG. 5.
However, in such method, a difference in level between the pressed surface 5k of the protruding portion 5j and the surface 5l of the metal sheet 5i is limited to 25% of the increased thickness of the tab. When the difference level exceeds about 25%, there are disadvantages that it is liable to cause a crack in the metal sheet due to plastic deformation caused around the portion of the difference in level. In addition, it is also liable to cause a deterioration in electrical conductivity and lack of contactive reliability to the female terminal due to deterioration in the hardness of the metal plate. Further, it is impossible for the method to form a tab having relatively thin thickness for the metal sheet.
On the other hand, in the latter method, there exists such a problem that it is necessary to use a press machine with great capacity, therefore it is difficult to produce a male terminal having a wide tab area in the light of manufacturing and cost.